The social network has a "disproportionately wealthy user base," McDermottwrites, citing the analytics company comScore.

"More than 40% of LinkedIn visitors earn more than $100,000 per year," he continues, "higher than 31% average for the entire web."

By positioning itself as the place for white-collar workers to network, LinkedIn has commanded the eyeballs of lots of wealthy people, with nearly 80 million unique visitors a month. Its content strategy is now helping to turn those users into loyal readers, making the social network that much more attractive to advertisers.